It is known that an organic polymer having at least one reactive silicon group in the molecule undergoes crosslinking by formation of siloxane bonds accompanying a hydrolysis reaction of the reactive silicon group with moisture or the like even at room temperature, and a rubber-like cured article can be obtained.
Among the polymers having a reactive silicon group, organic polymers in which the main chain skeleton is a polyoxyalkylene polymer or an isobutylene polymer are disclosed in (Patent Document 1), (Patent Document 2) and the like. Those polymers have already been industrially produced, and are widely used in applications to sealants, adhesives, coatings and the like.
Curable compositions comprising the above described organic polymers having a reactive silicon group are cured by using silanol condensation catalysts, and usually organotin catalysts having a carbon-tin bond such as dibutyltin bis(acetylacetonate) are widely used. However, in recent years, toxicity of organotin compounds is pointed out, and development of non-organotin catalysts are demanded.
With respect to curable silicone compositions prepared using a titanium compound as a non-organotin catalyst, so far many investigations have been made, and are disclosed in (Patent Document 3) and the like. At an initial stage of the investigations, when a titanium compound was used as a curing catalyst, there were many problems with curability, storage stability, an extreme increase in viscosity when silicone came into contact with a titanium catalyst, and the like. As described in (Patent Document 4), (Patent Document 5), (Patent Document 6), (Patent Document 7) and the like, as a result of various investigations made, improvement methods such as modification of a silicone-terminated structure, use of a chelate type titanium compound, and the like have been found, and at the present time, dealcoholization type silicone compositions using titanium catalysts are widely used in a variety of applications.
However there are relatively few examples of adding a titanium catalyst to a reactive silicon group-containing organic polymers. Those examples are disclosed in (Patent Document 8), (Patent Document 9), (Patent Document 10), (Patent Document 11), (Patent Document 12), (Patent Document 13), (Patent Document 14), (Patent Document 15), (Patent Document 16) and (Patent Document 17).
On the other hand, various properties such as curability, adhesion and mechanical properties are demanded for curable compositions used for a sealant, an adhesive, a coating and the like and rubber-like cured articles obtained by curing the compositions. Also with respect to organic polymers having a reactive silicon group, so far many investigations have been made.
As a result, now it is already known that by adding a plasticizer such as phthalic acid ester or the like to a curable composition, suitable mechanical properties such as a modulus, an elongation at break and a strength at break can be obtained in the respective applications. Additionally, (Patent Document 18), (Patent Document 19), (Patent Document 20), (Patent Document 21) and the like disclose techniques for solving, by using a high molecular weight plasticizer as a plasticizer, problems with bleeding out of a plasticizer, slump property, coating property of an alkyd coating material, storage stability and the like which arise when using a low molecular weight plasticizer.
Patent Document 1: JP-52-73998A
Patent Document 2: JP-63-6041A
Patent Document 3: JP-39-27643B (U.S. Pat. No. 3,175,993)
Patent Document 4: U.S. Pat. No. 3,334,067
Patent Document 5: JP-56-14701B
Patent Document 6: JP-55-43119A
Patent Document 7: JP-2-133490A
Patent Document 8: JP-58-17154A
Patent Document 9: JP-11-209538A
Patent Document 10: JP-5-311063A
Patent Document 11: JP-2001-302929A
Patent Document 12: JP-2001-302930A
Patent Document 13: JP-2001-302931A
Patent Document 14: JP-2001-302934A
Patent Document 15: JP-2001-348528A
Patent Document 16: JP-2002-249672A
Patent Document 17: JP-2003-165916A
Patent Document 18: JP-60-8024B
Patent Document 19: JP-63-108058A
Patent Document 20: JP-1-279958A
Patent Document 21: JP-9-176481A